Application of electrical signals to occipital nerves (occipital nerve stimulation or “ONS”) via implantable electrical signal generators has been shown to be effective in treatment of chronic migraine in some patients and has potential for treatment of other types of headache. While promising, initial studies have shown that only about 40% of patients with medically refractory chronic migraine receive benefits from ONS. Improving this responder rate through patient screening would be beneficial to the patient. That is, a patient who is not a viable candidate could avoid an unnecessary procedure and surgery associated with implantation of an electrical medical device system. One method that has been used to screen candidates for ONS employs a trialing system that includes a percutaneously inserted lead and an externalized electrical signal generator. Although this practice is common, it does not appear to have a high positive predictive value as to whether the patient will respond to ONS via an implantable system.
The exact mechanism of how ONS treats migraine is not well understood. It is believed that many types of headache are associated with nociceptive pathways of the trigeminal nerve and that the therapeutic effect of ONS may be due to convergence of occipital afferents and trigeminal afferents in the lower brain stem/upper cervical region, such as the trigeminal cervical complex. Via this convergence. ONS may have an inhibitory effect on nociception transmitted via trigeminal afferents, which may then have a pain-relieving effect on migraine or other types of headache.